Friction brake



.1. WHY-rE FnIcTIoN BRAKE June 7, 1932.

Filed Feb. 17, 1930 2 Sheets-Sheet 1 June 7, 1932. J. wHYTE FR ICTION BRAKE 2 Sheets-Sheet 2 Filed Feb. 1f(

M www@ Patented June 7, 1932 UNITED STATES PATENT OFFICE JOHN WHYTE, OF IBELOIT, WISCONSIN, ASSIGNOR TOMWABNER ELECTRIC BRAKE COR- PORATION, OF SOUTH IBELOIT; ILLINOIS, A CORPORATION OF ILLINOIS FRIGI'ION BRAKE This invention relates to friction brakes of the drum type such as are used on automotive vehiclesand has more particular reference to an electric brake in which almomentum operator comprising two annular magnetic rings is embodied within the drum so that the brake and operator form a unitary structure capable of being mounted on a vehicle wheel.

One' object of the present invention isvto provide a brake of the above character in which the actuating force derived by the operator is applied to the braking means proper in a truly circumferential direction through the medium of a novel actuating mechanism which is so constructed and associated with 'the anchorage for the brake proper as to minimize the overall radial width of the brake and operator unit.

Another object is to provide a novel anchoring means for a brake of the full wrap band type which anchora-ge renders the band effective throughout'its entire length.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connec- -tion with the accompanying drawings, in

` which:

Figure 1 is a vertical sectional view of a vehicle wheel equipped with a brake embodying the features of the present invention, the section being taken substantially along the line 1--1 of Fig. 2.

Figs. 2 and 3 are sectional views taken along the lines 2--2 and 3-3 respectively of Fig. 1.

Fig. 4 is a fragmentary sectional view taken along the line 4-4 of Fig. 2.

While the .invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is tobe understood that I do not thereby int-end to limit the invention to the speciiic form disclosed, but intend to cover all modifications and alternative constructions falling Within the spirit and scope of the invention as expressed in the appended claims.

In the exemplary form shown in the drawings the ,invention is embodied in an electric brake including a rotatable drum 6 having the usual flange 7 bolted or otherwise secured to the inner end of a hub 8 of a vehicle wheel 9. The inwardly opening end of the drum is partially closed by an annular plate l1 suitably secured toa steering knuckle 12 or other relatively non-rotatable part.l Integral with the outer peripheral edge of the anchor plate 11 is an annular flange 13 which projects into and is of a diameter slightly less than that of the drum. A separately formed ring 14 welded to the outer portion of the anchor plate o-verlies the edge of the drum and completely closes its open end.

In the present instance the non-rotatable part of the brake is of the band type comprising ametal strip 15 encircling the flange 13 on the anchor plate and carrying segments 16 of suitable friction material on its outer surface. The adjacent ends-of the band are spaced a art so as to leave a vacant sector at one si e of the drum and each is equipped with a fitting 17 comprising two spaced plates 18,.extending along the Yinner surface of the strip 15 on opposite sides of its longitudinal center line. Lugs 19 on theplates project into apertures in the strip and securely hold the fittings and strip against relative movement. l

The plates 18 are rigidly joined at 20 and` project through an elongated slot 21 `in the anchor iiange 13. The slot is of suflicientv surfaces 22 of a stop- 23, also of U-shaped cross-section. The latter projects through the slot 21 and has arms 24 (Fig. 1) which are securely fastened against the flange'13 as by welding.

The fittings 17 are drawn toward each other and therefore normally held in abutment with the end surfaces of the stop by `a. contractile spring whose opposite ends arev hooked.A around cross members 26 between the flared ends of the plates 18. The spring 25 is located in the vacant drum sector between the `ends of the band and therefore may |be readily after the band and all of the other vparts of the brake have been assembled on the flange 13. r YFrom Figs. 1

and 4 it will be noted that the spring is dis# rial arranged concentric with the drum and adapted. for .l axial gripping engagement. VThe ring 27, which constitutes the magnetic armature, isof rectangular cross sectional shape and relatively narrow axial width. Preferably this ring is of solid metal construction and floatingly sup rted from the drum so as to rotate therewith, at the same time being adapted for some de ee of axial ,movement To this end, the ba is secured at annularly spaced points to the of the ring ends-of flexible metal stri s 29 which extendin a direction Y substantia y tangent to the ring 27 and are rigid at their other ends with a ring 30 in turn riveted to the drum flange 7. When the wheel and drum with the armature unit mounted thereon are placed on the` axle, the inwardly facing friction faceof the armature ring is pressed lightly a ainst the friction face of the magnet ring 28 y springs 31 actingfin 'compression between the rings 27- and 30.

' The rin 28 constitutes the magnet proper and is U- aped in cross section with a winding 32 dis osed between its twovconcentric po es 33, w ich are separated by plates 34 of non-magnetic material providing a wear resisting surface substantially flush with the end faces of the poles and adapted to sustain the axial pressure between the twomagnetic rings. T e magnet is supported by the anchor plate for oscillation about .the

away y from normal Projecting rigidly from'the outer ma et pole are two circumferentially spaced ugs 35 which extend into tlie space between the plates 18 of the band iittings 17 and provide oppositely facing abutments 36. which are spaced ircumferentially to correspond to the spacing of the opposed shoulders formed on. the band fittings by blocks 37 welded between the remote-@ends of the plates 18.v Upon movement o f the magnet in either direction rake-released position (Fig. 2), one or the other ofthe lugs 35 will move its end of the band away from the stop 23 thereby expanding the band and pressin its entire surface against the drum. Eac abutment 36 and the cooperating shoulder engaged thereby are slightly inclined with `respect to a true radial plane intersecting the abutment so that the actuated end of the band will not .be held against outward movement by the lug 35 dueto slight manufacturing inaccuracies in locating the abutment. It will be observed Ithat the lugs v35 coincide with and therefore apply the actuating force along the longitudinal center line of the band. Each is adapted for a substantial deree of circumferential movement relative to its coacting block 37- by reason of the open slot between such block and the cross member 26.

When the magnet winding, 32 is energized the magnetic attraction thus produced causes gripping engagement between the friction surfaces of the two rings proportional to the strength of the energizing current, whereupon the magnet ring will be 'driven frictionally b A the armature ring, thereby moving with t e wheel a -short angular distance. In this movement one end ofthe band is moved awa from the stop 23 which expands the ban .thereby pressing the Y segments 16 against the drum surface. After the normal -clearance has beenvtaken up angular movement of the magnet ceases, causing slippage between the ring surfaces-in the continued rotation of the wheel. When tlie current iiow is interrupted the spring 23 acting through the medium of the fitting 17`and the active lug 35 serves to restore the magnet as well as the actuated end of the band to normal brakereleased position. Y

By thel employment of two 'circumferentially spaced actuating lugs 35 acting on the band at points spaced from the ends thereof,

Preferably 'the end surfaces 22 of the stop i. 23 are also. inclined relative to true radial planes intersecting them. VPreferably the amount of this inclination is slightly greater than the angle of repose of the two metal surfaces. As shown in Fig; 3, th direction of.

the inclination of the surface-22-relative to a radial line'39 is such that the active stop surface 22 exerts a camming or wedging action on the anchored end of the land fitting with the result that suchend of the band is thrown outwardly again/St thejdrum and sustains its share of the braking pressure. Thus, it will be apparent that the entire length of the band is available for the development of a powerful wrapping action regardless of the direcnetic ringsof larger diameter and therefore greater eifectiveness and also provides for a recess in the anchor plate which 1s large `enough to accommodate steering knuckle constructions of widely varying sizes. At the same time large and ruggedly mounted anchoring surfaces are-provided with the present construction which enables the entire lengthof the band to come into action and effectually prevents unnecessary vibration of the band when engaging the drum surface.

I claim as my invention:

1. A brake comprising a rotatable drum, a band extending around the internal drum surface and having adjacent separable end portions, a stop between said end portions, a spring stretched between said end portions and normallyr drawingl the same into abutting engagement with said stop, a pair of opposed shoulders rigid with opposite end portions of said hand and disposed substantially in radial positions, actuating means for said band including a magnetic ring concentric with the drum axis and movable in opposite directions away from a normal brake-released position, a pair of lugs rigid with and proj ecting outwardly from said ring at a point coincident with the longitudinal center line of said band, and a pair of outwardly facing abutments on said ring both engageable with said shoulders when both ends of the band. areengafring said stop, said spring acting through the medium of s aid lugs to maintain said ring in normal brake-released position.

2. A brake of the character described combining a rotatable drum, a friction band extending around the inner drumsurface, a stop positioned between the adjacent ends of t said band, spring means normally drawing said ends into abutting engagement with said stop, a pair of magneticfrictionrings disposed within said drum and concentric therewith, one of said rings being rotatable with the drum, the other being mounted for limited oscillation about the drum axis, and a pair of lugs rigid with and projecting outwardly from the latter friction ring and adapted upon oscillation of the ring in opposite directions to move one end or the other of said bandv away from said stop, said lugs being spaced circumferentially. from said stop.

3. A brake of the character described combining a drum, a non-rotatable stop disposed adjacent the internal drum surface, a band extending around said surface and having I its adjacent end portions arrangedv for abutting engagement with said stop, a pair of friction rings within said drum, one rotatable with the drum, the other being arranged for limited oscillatory movement about a drum axis when brought into gripping engagement With the other elelnent, and meansrigid with said oscillatory element for bringing onev end or the other of said'band away from said stop whereby to expand the band against the drum, said last mentioned means and said stop being spaced apart circumferentially of the drum so as to permit said rings and said lband to be located closetogether.

4. A brake of the character described combining a rotatable'j drum, anchoring means having oppositely facing stop surfaces, a friction braking element extending around the internal cylindrical surface of said drum with its adjacent end portions normally abutting against said surfaces, an annular actuating member concentric with said'element 'and arranged for limited movement about the drum axis and in opposite' directions from a normal'brake-released position, a pair of opposed shoulders on opposite ends of said element, and a pair of oppositely facing abutments on said member spaced circumferentially from said stop surfaces and each adapted upon movement of the member in one direction to engage one of said shoulders and move its end of fthe braking element. away from said anchoring means, said stop surfaces and said abutments being substantially equidistant from the drum axis and overlappingV each other so as to increase the radial compactness of the brake and actuating unit.

5. A brake of the character described combining a rotatable drum, a. friction band extending around the cylindrical' surface of said drum with its ends disposed adjacent each other on one side of the drum, a non-V rotatable stop of relatively shortV circumferential length prcsentin end surfaces against which the ends of sai band are normally held in abutting engagement so that one end or the other may be moved away from the stop to bring the band into gripping engagement with the drum, and actuating means for said band including an annular' member. movable about the axis 'and-engageable with the respective ends of the band at points spaced circumferentially from the points of engagement between said ends and said stop,

said member vactingupon movement in either direction from a normal brake-released position to move one of said ends away from said stop and thereby apply the brake.

6. .A brake of the character ldescribed cornbin'ing a rotatable drum, a friction band ex- 4 tending around the drum, a non-rotatable stop against which the end portions of said band are normally held in abutting engage'- ment, two opposed shoulders, one on each end portion of said band spaced from the end of the band, and a circumferentially movable actuating member havin oppositely facing drum with itsends disposed adjacent each other, a non-rotatable stop having axially of said'band, actuating means spaced side rtions, the ends of which form a utments or engaging the op osite 'ends ibr moving One end or theother of said band away from its abutment, and a contractile sprin disposedv between the side portions of sai stop nddstretched between opposite ends of said 8. A brake of the character described combining a rotatable drum, a friction band extending around the internal surface of said drum with its ends disposed adjacent e'ach other, anon-rotatable stop disposed between opposite ends of said band closely adjacent the inner drum surface, a spring normally drawing the opposite ends of said band into abutting engagement with said stop, and ac- ,Ituating means for moving one end or the ranged for abuttxn other of said band away from said stop against the action ofsaid spring, saidspring and said stop being disposed equi-distant frompthe drum axis and both actin on said band along the longitudinal center llne there- 9. A brake combinin a rotatable drum, an anchor plate closing t e open end of said drum, a flange on said anchor plate project- 1n into the drum closely adjacent the interm5 surface thereof, a friction band extending aroundsaid internal surface and having adjacent end portions dis osed between` said ange and drum, said an e having cumferential slot therein adjacent sald ends, a non-rotatable stop having spaced side portions rigid with said iange and disposed on opposite sides of said slot, said side portions having oppositely facing end surfaces arengagement with the ends of said ban a contractile spring stretched between the ends of said band and located in said slot between the side portions of Said stop, and means dis osed within said flange and movable circum erentially of said drum to move one end or the other of said band away from said'stop.`

`10. A brake combinin a rotatable drum, an anchor plate lclosing t e .open end of said drum, a flange on said anchor plate projecting into the drum closely adjacent the internalsurface thereof, a friction band extends a cirreleased adjacent end portions between said ange and drum, said dan having a circum-4 ferentil slot therein adjacent sald ends, a-

said band and projecting inwardly through said slot so as to be guided therein,` and a c1rcumferentially movable actuating member Alocated within said flange and having t`wo olppositely facing abutments engageable with t e respective fittings so as to move one end or the other of the band'away from said stop upon movement of said member in either d1,- rection, v f Y 11. A brake of the character described combining a rotatable drum, a bandextending around the internal drum surface, a nonrotatable sto against which the adjacent ends of said and are normally drawn, said ends having opposed shoulders, an actuating member located within said band and movable circumferentiall in opposite directions from a normal birake-released position, and a pair of oppositely facing abutments on said member en ageable with said shoulders, said abutments aving surfaces inclined relative to a radial plane intersecting them so that the abutment allows the acw,tuated end of said bandto move outwardly V`z 'giainst the drum surface during actuation plates extending longitudinally of the band onjshe inner iside thereof, a non-rotatable stop having axially spaced side portions, the ends of which are arranged for abutting enga ement with the opposing end portions of t e plates comprisin said fittings, a contractile spring disposed tween the side portions of said stop with its ends extending intoV the space between the plates of said fittings, the opposite ends of said spring being attached to said fittings, an annular actuating member concentric with the drum, and a pair of lugs rigid with said member and each projecting into the space between the plates of one of said fittings, said lugs cooperating with shoulders on saidfittings so as to `move one end or the other of the band away from said stop upon movement of said member in either direction away from a normal brakeition. 13. A Itii'sake of the character described combining a rotatable drum, a friction band extending around the internal drum surface and havin fittings rigid withl its o posite ends, each tting comp a pair of) axiall spaced plates extending longitudinally of 65 ing around said internal surface and having t e band on the inner side thereof, a non-ro- 130 tatable stop against which the adjacent ends of said fittings abut an annular actuating member concentric with the drum, and a pair of lugs rigid with said member and each projecting into the space between the plates of one of said fittings, said lugs cooperating with shoulders on said fittings so as to move one end or the other of the band away from said stop upon movement of said member in v either direction away from normal brake-released position.

In testimony whereof, I have hereunto affixedm si ature.

y, gn JOHN WHYTE. 

